Ruby

Variables

Uses sigils for scoping. This is just a language convention, but libraries often provide names based on these patterns so they are effectively language features.

• x is a local variable (or something other than a variable).
• $x is a global variable.
• @x is an instance variable.
• @@x is a class variable.

Uses sigils for typing sometimes. This is just a convention I think.

• varname? means boolean
• action! means potentially dangerous?

:name is a "symbol". Symbols are immutable values where any two symbols given the same name will be identical. Makes comparisons quicker since its just a pointer check. More details.

Blocks

begin/rescue blocks are similar to try/catch blocks in other languages.

begin
  # Code that may raise an exception
rescue SomeException => e
  # Handle SomeException
rescue AnotherException => e
  # Handle AnotherException
else
  # Code to run if no exceptions occurred
end

You can omit begin if you attach the rescue block to a method

  def authenticate_jwt
    token = request.headers['Authorization'] || ''
    token = token.delete_prefix('Bearer ')

    @jwt_payload = JWT.decode(token, nil, false).first
  rescue JWT::DecodeError
    head(:unauthorized)
  end

Misc Syntax

:: is used to access values from a namespace.

NameOfNamespace::Child

# force usage of global namespace
::Time.zone.now